Final answer:
Katy's college sorority is a reference group to her, as it is the group whose values and norms she follows in hopes of becoming a member, unlike the literature club which she does not identify with.
Step-by-step explanation:
In the scenario described, Katy's college sorority is an example of a reference group. A reference group is a group whose values, norms, and beliefs come to serve as a standard for one's own behavior. Given that Katy aligns her behavior with the norms and values of the sorority in anticipation of becoming a member, it represents a standard she aspires to and compares her own actions against. This is distinct from her current membership in the literature club, which she does not view as a group that she identifies with or wants to emulate.
While an ingroup consists of members with whom an individual identifies closely, and she views the group as an integral part of her identity, an outgroup is seen as a group one does not belong to and may even be in competition with. In Katy's case, the literature club could be considered an outgroup since she neither accepts nor follows its values. Similarly, primary and secondary groups differentiate in the level of intimacy and the nature of relationships, but for Katy's situation, the sorority is best understood as a reference group influencing her behavior.